The present disclosure is directed to high pressure fluid cleaning lance handling systems. In particular, embodiments of the present disclosure are directed to an apparatus for advancing and retracting one or more flexible tube cleaning lances from tubes arranged in an array, such as in a heat exchanger, from a position adjacent a heat exchanger tube sheet.
A flexible lance drive apparatus typically includes a drive motor coupled via gearing, a chain, or a belt to one or more drive mechanisms. Drive mechanisms can be rollers that are arranged in pairs or sets sandwiching a flexible lance hose therebetween or chain and block assemblies oriented with interlocking top and bottom assemblies. At least one roller of the sets of rollers, or chain and block assemblies may be driven. In order to accommodate different diameter lance hoses, the rollers or chain and block assemblies must be laboriously disassembled and replaced, and it may be necessary to modify the drive motor as well to accommodate the characteristics of a different driven lance hose. Additionally, once a mechanism has been properly configured for a given lance hose size, the distance between opposing drive mechanism roller pairs as the force that a given pair exerts on a lance hose is typically adjusted via a manual mechanical adjustment.
U.S. Pat. No. 9,070,830, for example, teaches a drive apparatus which requires the lance itself to be bent around a portion of the drive wheel in order to ensure sufficient drive force is transferred to the lance itself, especially in real world environmental application scenarios which are often less than ideal. Furthermore, such drive apparatuses are large, bulky, and thus must be either separately located on a floor near the heat exchanger tube sheet into which the lance or lances are supposed to be guided, as is shown in that publication, or rigidly mounted to a tray spaced from and aligned with the tube sheet. In such cases the tube bundle is typically physically removed from the heat exchanger and placed in an environment with sufficient space to accommodate the tray and drive assembly.
A lance drive mechanism incorporating a pair of opposing endless belts is disclosed in US Patent Application Publication 2010/0300498. This apparatus includes two opposing, segmented, endless belts above and below a flexible lance. Each of the belts has a V shaped groove in which the lance being driven resides. A pair of opposing platform clamps are used to push the endless belts against the lance(s) in the V shaped grooves of the belt. This generates a substantial drag on the endless belt that must be overcome by the power of the drive motor or motors.
What is therefore needed is a compact package drive solution that takes up a minimal space, can be mounted directly to an x-y lance positioner, facilitates simplified handling of multiple lances and several different sized flexible lance hoses interchangeably, can operate consistently under a variety of operating conditions, can be optimized for performance remotely, and remains simple to repair, service and modify for a variety of applications.